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<?php defined('SYSPATH') OR die('No direct access allowed.');
/**
* The Encrypt library provides two-way encryption of text and binary strings
* using the MCrypt extension.
* @see http://php.net/mcrypt
*
* $Id$
*
* @package Core
* @author Kohana Team
* @copyright (c) 2007-2008 Kohana Team
* @license http://kohanaphp.com/license.html
*/
class Encrypt_Core {
// OS-dependant RAND type to use
protected static $rand;
// Configuration
protected $config;
/**
* Returns a singleton instance of Encrypt.
*
* @param array configuration options
* @return Encrypt_Core
*/
public static function instance($config = NULL)
{
static $instance;
// Create the singleton
empty($instance) and $instance = new Encrypt((array) $config);
return $instance;
}
/**
* Loads encryption configuration and validates the data.
*
* @param array|string custom configuration or config group name
* @throws Kohana_Exception
*/
public function __construct($config = FALSE)
{
if ( ! defined('MCRYPT_ENCRYPT'))
throw new Kohana_Exception('encrypt.requires_mcrypt');
if (is_string($config))
{
$name = $config;
// Test the config group name
if (($config = Kohana::config('encryption.'.$config)) === NULL)
throw new Kohana_Exception('encrypt.undefined_group', $name);
}
if (is_array($config))
{
// Append the default configuration options
$config += Kohana::config('encryption.default');
}
else
{
// Load the default group
$config = Kohana::config('encryption.default');
}
if (empty($config['key']))
throw new Kohana_Exception('encrypt.no_encryption_key');
// Find the max length of the key, based on cipher and mode
$size = mcrypt_get_key_size($config['cipher'], $config['mode']);
if (strlen($config['key']) > $size)
{
// Shorten the key to the maximum size
$config['key'] = substr($config['key'], 0, $size);
}
// Find the initialization vector size
$config['iv_size'] = mcrypt_get_iv_size($config['cipher'], $config['mode']);
// Cache the config in the object
$this->config = $config;
Kohana::log('debug', 'Encrypt Library initialized');
}
/**
* Encrypts a string and returns an encrypted string that can be decoded.
*
* @param string data to be encrypted
* @return string encrypted data
*/
public function encode($data)
{
// Set the rand type if it has not already been set
if (Encrypt::$rand === NULL)
{
if (KOHANA_IS_WIN)
{
// Windows only supports the system random number generator
Encrypt::$rand = MCRYPT_RAND;
}
else
{
if (defined('MCRYPT_DEV_URANDOM'))
{
// Use /dev/urandom
Encrypt::$rand = MCRYPT_DEV_URANDOM;
}
elseif (defined('MCRYPT_DEV_RANDOM'))
{
// Use /dev/random
Encrypt::$rand = MCRYPT_DEV_RANDOM;
}
else
{
// Use the system random number generator
Encrypt::$rand = MCRYPT_RAND;
}
}
}
if (Encrypt::$rand === MCRYPT_RAND)
{
// The system random number generator must always be seeded each
// time it is used, or it will not produce true random results
mt_srand();
}
// Create a random initialization vector of the proper size for the current cipher
$iv = mcrypt_create_iv($this->config['iv_size'], Encrypt::$rand);
// Encrypt the data using the configured options and generated iv
$data = mcrypt_encrypt($this->config['cipher'], $this->config['key'], $data, $this->config['mode'], $iv);
// Use base64 encoding to convert to a string
return base64_encode($iv.$data);
}
/**
* Decrypts an encoded string back to its original value.
*
* @param string encoded string to be decrypted
* @return string decrypted data
*/
public function decode($data)
{
// Convert the data back to binary
$data = base64_decode($data);
// Extract the initialization vector from the data
$iv = substr($data, 0, $this->config['iv_size']);
// Remove the iv from the data
$data = substr($data, $this->config['iv_size']);
// Return the decrypted data, trimming the \0 padding bytes from the end of the data
return rtrim(mcrypt_decrypt($this->config['cipher'], $this->config['key'], $data, $this->config['mode'], $iv), "\0");
}
} // End Encrypt
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